Pressure Calculator & Converter – PSI to Bar, kPa, MPa | OmniCalculator.Space

  • Adam
  • November 27, 2025

Free pressure calculator from OmniCalculator.Space converts PSI, bar, kPa, MPa, atm & calculates hydrostatic, gauge, absolute pressure. Includes PSI to bar converter, kPa to PSI calculator, atmospheric pressure by altitude. Instant accurate results.

Pressure Calculator & Converter - PSI, Bar, kPa, MPa | OmniCalculator.Space

The comprehensive pressure calculator from OmniCalculator.Space converts between all major pressure units (PSI, bar, kPa, MPa, atm, mmHg) and calculates pressure from force, area, depth, and altitude. Whether you need a PSI to bar converter, hydrostatic pressure calculator, or atmospheric pressure converter, this all-in-one tool provides instant accurate results with detailed formulas.

Multi-Purpose Pressure Calculator

Results:

What is Pressure?

Pressure is the force applied perpendicular to the surface of an object per unit area, measured in pascals (Pa), PSI, bar, or other units. Understanding pressure is fundamental to fluid mechanics, engineering, meteorology, and everyday applications from tire pressure to blood pressure. The OmniCalculator.Space pressure calculator helps you work with all pressure units and calculations efficiently.

Key Characteristics of Pressure:

  • Scalar quantity: Has magnitude but no direction
  • SI unit: Pascal (Pa = N/m²), commonly using kPa or MPa
  • Imperial unit: PSI (pounds per square inch)
  • Acts equally: Pressure acts equally in all directions in fluids
  • Increases with depth: Hydrostatic pressure increases linearly with fluid depth
  • Temperature dependent: Gas pressure varies with temperature (ideal gas law)

Pressure Formulas

Master these fundamental pressure equations used in the OmniCalculator.Space pressure calculator:

Basic Pressure Formula

P = F / A

Where:

  • P = pressure (Pa or PSI)
  • F = force (N or lbf)
  • A = area (m² or in²)

Hydrostatic Pressure Formula

P = ρgh

Where:

  • P = hydrostatic pressure (Pa)
  • ρ = fluid density (kg/m³)
  • g = gravitational acceleration (9.81 m/s²)
  • h = depth or height of fluid column (m)

Gauge and Absolute Pressure

Pabsolute = Pgauge + Patmospheric

Standard atmospheric pressure = 101.325 kPa = 14.7 PSI = 1.01325 bar

Atmospheric Pressure by Altitude

Barometric formula (simplified):

P = P₀ × (1 - Lh/T₀)gM/RL

Or approximately: P ≈ P₀ × e-h/H where H ≈ 8,500 m

Pressure Unit Conversion Table

Quick reference for converting between common pressure units with the OmniCalculator.Space converter:

Unit to Pa to PSI to bar to atm
1 Pa 1 0.000145 0.00001 0.00000987
1 PSI 6,894.76 1 0.0689476 0.068046
1 bar 100,000 14.5038 1 0.986923
1 atm 101,325 14.6959 1.01325 1
1 kPa 1,000 0.145038 0.01 0.00986923
1 MPa 1,000,000 145.038 10 9.86923

Types of Pressure

Understanding different pressure types is essential for proper measurements and calculations:

Absolute Pressure

Absolute pressure is measured relative to perfect vacuum (zero pressure). It's always positive and equals gauge pressure plus atmospheric pressure. Used in thermodynamic calculations and gas laws.

Gauge Pressure

Gauge pressure is measured relative to atmospheric pressure. Most pressure gauges and tire pressure measurements are gauge pressure. Can be positive (above atmospheric) or negative (vacuum).

Differential Pressure

The difference between two pressure points, commonly used in flow measurements, filter monitoring, and HVAC systems. ΔP = P₂ - P₁.

Hydrostatic Pressure

Pressure exerted by a fluid at rest due to gravity. Increases linearly with depth according to P = ρgh. Critical for dam design, submarines, and diving.

Atmospheric Pressure

Pressure exerted by Earth's atmosphere. Standard sea level value is 101.325 kPa (14.7 PSI, 1 atm, 1.01325 bar). Decreases with altitude.

Common Pressure Conversion Examples

PSI to Bar Conversion

Formula: bar = PSI × 0.0689476

Example: Convert 50 PSI to bar

bar = 50 × 0.0689476 = 3.447 bar

Common conversions:

  • 30 PSI = 2.07 bar (typical car tire)
  • 100 PSI = 6.89 bar
  • 14.7 PSI = 1.01 bar (atmospheric)

kPa to PSI Conversion

Formula: PSI = kPa × 0.145038

Example: Convert 250 kPa to PSI

PSI = 250 × 0.145038 = 36.26 PSI

MPa to PSI Conversion

Formula: PSI = MPa × 145.038

Example: Convert 5 MPa to PSI

PSI = 5 × 145.038 = 725.19 PSI

Pressure Calculation Examples

Example 1: Pressure from Force and Area

Problem: A 5000 N force acts on an area of 0.5 m². Calculate the pressure.

Solution:

P = F/A = 5000 N / 0.5 m²

P = 10,000 Pa = 10 kPa = 1.45 PSI

Example 2: Hydrostatic Pressure

Problem: Calculate water pressure at 10 meters depth.

Solution:

Given: ρ = 1000 kg/m³, g = 9.81 m/s², h = 10 m

P = ρgh = 1000 × 9.81 × 10

P = 98,100 Pa = 98.1 kPa = 14.23 PSI

Total absolute pressure = 98.1 + 101.325 = 199.425 kPa

Example 3: Gauge to Absolute Pressure

Problem: A tire gauge reads 35 PSI. What is the absolute pressure?

Solution:

Pabsolute = Pgauge + Patmospheric

Pabsolute = 35 + 14.7 = 49.7 PSI

Pabsolute = 49.7 PSI = 342.6 kPa = 3.43 bar

Applications of Pressure Calculations

The OmniCalculator.Space pressure calculator serves numerous practical applications:

  • Automotive: Tire pressure monitoring, hydraulic brake systems, engine compression
  • HVAC: Duct pressure drop, air flow calculations, system balancing
  • Hydraulics: Cylinder force calculations, pump sizing, system design
  • Diving: Depth pressure calculations, decompression planning, gas mixture planning
  • Aviation: Altitude pressure calculations, cabin pressurization, altimeter settings
  • Medical: Blood pressure measurement, respiratory pressure monitoring
  • Industrial: Pneumatic systems, pressure vessel design, safety valve sizing
  • Meteorology: Barometric pressure tracking, weather forecasting, storm prediction

Frequently Asked Questions

How do you convert PSI to bar?
To convert PSI to bar, multiply by 0.0689476. The formula is: bar = PSI × 0.0689476. For example, 50 PSI = 50 × 0.0689476 = 3.447 bar. For quick approximation, divide PSI by 14.5 to get bar. The OmniCalculator.Space pressure converter handles this conversion instantly along with many other units.
What is the difference between gauge pressure and absolute pressure?
Gauge pressure is measured relative to atmospheric pressure, while absolute pressure is measured relative to perfect vacuum. The relationship is: Pabsolute = Pgauge + Patmospheric. Most pressure gauges read gauge pressure. At sea level, atmospheric pressure is approximately 101.325 kPa (14.7 PSI, 1.01325 bar). A tire gauge reading 30 PSI means 30 PSI gauge, which equals 44.7 PSI absolute.
How do you calculate hydrostatic pressure?
Hydrostatic pressure is calculated using P = ρgh, where ρ is fluid density (kg/m³), g is gravitational acceleration (9.81 m/s²), and h is depth (m). For water at 10 m depth: P = 1000 × 9.81 × 10 = 98,100 Pa = 98.1 kPa. This is the pressure increase due to depth; add atmospheric pressure for total absolute pressure. The OmniCalculator.Space hydrostatic calculator handles all fluid types and depths.
How many PSI is 1 bar?
1 bar equals 14.5038 PSI. To convert bar to PSI, multiply by 14.5038. For example, 3 bar = 3 × 14.5038 = 43.51 PSI. Conversely, 1 PSI = 0.0689476 bar. Bar is commonly used in Europe and international standards, while PSI is prevalent in the United States. Both units are widely used for tire pressure, hydraulic systems, and pneumatic equipment.
What is the formula for pressure?
The basic pressure formula is P = F/A, where P is pressure, F is force perpendicular to the surface, and A is area. In SI units, pressure (Pa) = force (N) / area (m²). For fluids at depth, use hydrostatic pressure formula P = ρgh. For gases, pressure depends on temperature and volume according to the ideal gas law PV = nRT. The OmniCalculator.Space pressure calculator uses all these formulas for comprehensive calculations.
How do you convert kPa to PSI?
To convert kPa to PSI, multiply by 0.145038. Formula: PSI = kPa × 0.145038. Example: 200 kPa = 200 × 0.145038 = 29.01 PSI. For reverse conversion, PSI to kPa, multiply by 6.89476 (kPa = PSI × 6.89476). Quick approximation: 100 kPa ≈ 14.5 PSI. This conversion is essential for international automotive work, as European specifications use kPa while American use PSI.
What is atmospheric pressure at different altitudes?
Atmospheric pressure decreases approximately exponentially with altitude. At sea level: 101.325 kPa (14.7 PSI). At 1000 m: ~89.9 kPa. At 2000 m: ~79.5 kPa. At 5000 m: ~54 kPa. At 10,000 m: ~26 kPa. The barometric formula P = P₀(1 - Lh/T₀)^(gM/RL) provides accurate calculations. The OmniCalculator.Space altitude pressure calculator computes exact values for any elevation, essential for aviation, mountaineering, and meteorology.
How do you calculate force from pressure and area?
Rearrange the pressure formula P = F/A to get F = P × A. Multiply pressure by area to find force. Example: If pressure is 100 kPa (100,000 Pa) acting on 0.5 m² area, then F = 100,000 × 0.5 = 50,000 N. Ensure consistent units: Pa with m², PSI with in². This calculation is fundamental for hydraulic cylinder sizing, pneumatic actuators, and structural load analysis. Use OmniCalculator.Space for instant force calculations.
What is the relationship between MPa and PSI?
1 MPa = 145.038 PSI. MPa (megapascal) is 1 million pascals, commonly used for high-pressure applications like hydraulic systems and material strength specifications. To convert: PSI = MPa × 145.038, or MPa = PSI / 145.038. Example: 10 MPa = 1,450.38 PSI. Typical hydraulic systems operate at 10-35 MPa (1,450-5,075 PSI). The OmniCalculator.Space MPa to PSI converter handles these conversions accurately.
How does temperature affect pressure?
For gases in a fixed volume, pressure increases linearly with absolute temperature according to Gay-Lussac's Law: P₁/T₁ = P₂/T₂. Temperature must be in Kelvin (K = °C + 273.15). If gas temperature doubles (in Kelvin), pressure doubles. For example, tire pressure increases when driving due to heat from friction. A tire at 30 PSI at 20°C might reach 33 PSI at 50°C. The ideal gas law PV = nRT fully describes pressure-temperature-volume relationships for gases.

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